With a bat'leth in hand, an enraged B'Elanna Torres storms out of a holodeck, followed closely by Tom Paris. Torres resents the fact that Paris took her to a Klingon training session. She laments Paris' new-found interest in Klingon martial arts, and insists that she is not interested in holographic disembowelment. An argument between the two ensues. Paris calls Torres hostile. At that moment an alien is transported on to USS Voyager. The man appears to be lost and confused.

Shocked at the visitor, Paris signals the bridge. The alien appears frightened, and out of place in Voyager's artificial environment. He is brought to sickbay, where he is examined by The Doctor. The alien identifies his species as Nyrian. He claims to have been walking in the street when he was transported aboard. When inquired about how he came aboard Voyager, he described feeling lightheaded, everything around him "bending, or rippling", then a curious sensation. They soon realize that at the instant that the Nyrian was transported aboard Voyager, Kes was transported away. Concerned, CaptainJaneway orders Kim and Torres to start investigating. There are no indications that a ship could have transported them, and that the closest system is over ten light years away. EnsignKim is beamed away a few minutes later, and another Nyrian appears on the bridge. Nyrians are now regularly appearing on Voyager. At a senior staff meeting, it's revealed that in the last three hours, twenty-two people have disappeared, and that in eighteen hours, the entire crew will disappear. Torres explains that what is happening could have been anything, a naturally-occurring phenomenon or a kind of technology. She shows a surge in polaron particles, and a spatial distortion field surround the abductees before they disappear. Chakotay does not feel threatened and considers the Nyrians friendly, but Janeway has a gut feeling that something is wrong about them.

"Captain's log, Stardate 50912.4. It's been twelve hours since these mysterious exchanges began, and we still haven't discovered their cause. I've already lost over half my crew."

Concerned, Janeway has the Nyrians confined to the cargo bays and orders that all non-essential functions are to be shut down. In engineering, Torres has a theory that Voyager has snagged onto a wormhole the moment that it was forming. Soon, Janeway herself is beamed away. With a skeleton crew, Chakotay is left in command. He mans the helm and an ensign has tactical. Neelix is soon abducted while he is on the bridge. Chakotay has all computer interfaces restricted to Starfleetvoiceprints only. Torres is working with a Nyrian scientist, conducting a tetryon scan of the area against the scientist's objections. Torres concludes that the anomaly isn't a wormhole, nor is it a subspace flow field. The scientist, Rislan, strikes his security guard and grabs the guard's phaser. He then presses a few buttons on the control panel and says that she has been moved to the front of the line. She is transported to an idyllic version of Earth, along with the missing crewmembers.

The Nyrian security guards take her combadge and leave. Torres, Janeway, Kes, and Paris all swap theories on what is going on, and what the Nyrians want. Tuvok reports that the crew is spread across twelve different compounds and at all ends there is an insurmountable barrier, a cliff or a river. Paris says that their "paradise" has an almost idyllic quality.

Crewman Gennaro tells Chakotay that Rislan's guard, Ensign Molina, is unconscious in engineering and that Rislan and Torres are gone. Chakotay runs to the cargo bay to have a talk with the Nyrians. He draws his phaser and jumps into the room in an aggressive posture. The room is empty. He issues a security alert to the remaining twelve crewmen on board. The crew moves to secure engineering and the bridge, but it is futile. The Nyrians storm both stations and easily overpower the personnel there. Chakotay realizes that the Nyrians have planned this all along, so he orders the remaining Voyager crew to sabotage the ship, but they are soon beamed away. Chakotay finds that the Nyrians are trying to delete The Doctor's program and heads to sickbay. Arriving successfully, Chakotay transfers The Doctor to his mobile emitter as the Nyrians corner him. As he surreptitiously pockets the emitter, Chakotay surrenders and he is transported to the surface, allowing the Nyrians to have successfully taken over the ship.

Back at the prison compound, a Nyrian woman named Taleen appears and welcomes the Voyager crew to their new home. The Nyrians expand their civilization by gradually switching places with the crews of ships, space stations, and colonies and transport their victims to an artificial environment drawn from the victims' own databases. The Nyrians see themselves as benevolent jailers, but Chakotay remarks that it is "still a prison."

As soon as Taleen leaves, Janeway begins to plan their escape, theorizing that the entire place is likely to be a holographic projection. An alien named Jarlath appears to welcome the crew, saying he is their new neighbor.

Jarlath reveals that there are other environments holding different species and that each environment is tailored to the requirements of its prisoners. Jarlath has found a portal between his environment and the one holding the Voyager crew, and Janeway trades him a couple of baskets of food for the means to locate the portal.

That evening, Torres reconfigures the EMH's optical sensors to detect the microwave signature of the portals. She apologizes to Paris but an argument between the two ensues. The Doctor makes comments about the exchanges with psychological analysis until Torres reconfigures the EMH to make The Doctor mute. The EMH discovers a portal that leads into the control area of the prison colony. Janeway, Tuvok, Torres, Paris, and Jarlath enter the control area and split up, carrying home-made phasers "improvised" by Tuvok.

Janeway and Tuvok use a control station terminal and learn that there are 94 different environments, and that they are actually on a ship. Just as they learn more information, an alarm begins to sound.

The Nyrians are alerted to their presence outside their environment, and Dammar authorizes Taleen to use force to return the prisoners to their habitats. Dammar also orders Voyager to be taken to the biosphere vessel to reinforce them.

With Nyrian guards on their tail, Torres and Paris (minus the anxious Jarlath who surrenders to the Nyrian guards) are trapped inside the corridors of the Nyrian ship. They come to a frigid, snowy habitat and Torres recalls how the Nyrians found Voyager too cold. Assuming that the Nyrians would not want to pursue them, they enter the habitat. Taleen orders her guards to follow them. Using Tuvok's phaser, Torres and Paris manage to stun the guards, but then find themselves lost in the wintry landscape, unable to return to the portal.

Meanwhile, Janeway and Tuvok evade capture, and Tuvok uses the Vulcan nerve pinch on a Nyrian guard. They discovers the translocator that the Nyrians used to switch places with the Voyager crew, and attempts to gain command of it.

Just as Torres seems about to succumb to the cold, she and Paris find themselves back in the Earth habitat, and Dammar and Rislan find themselves in the icy Argala habitat. Janeway and Tuvok have learned how to use the translocator, and Janeway threatens to relocate all the Nyrians to the Argala habitat unless her crew and all the other prisoners are freed. Faced with death by hypothermia, the Nyrians surrender and relinquish Voyager to Janeway. The alien prisoners are freed, and their native worlds are contacted to take them home.

"Captain's log, stardate 50912.4. It's been twelve hours since these mysterious exchanges began. We still haven't discovered their cause. I've already lost over half my crew."

"Captain's log, stardate 50929.6. The Nyrians have surrendered Voyager, and my crew is safely back on board. The former prisoners on the habitat vessel have contacted their native worlds, and are waiting to be taken home."

"I've reconfigured The Doctor's optical sensors and as soon as they're aligned he should be able to detect the microwave signature of the portals."
"Then I can begin my new career as a tricorder."

- Torres and The Doctor

"Shows how much you know about Klingons. They have much less tolerance for the cold than Humans do."
"Really? I thought that was Cardassians."
"No, they just complain about it more."

- Torres and Paris inside the Argala habitat

"On your feet, that's an order!"
"You can't give me orders, we're the same rank."
"I'm a bridge officer, and I have seniority."
"Yeah, by about two days!"

- Paris and Torres

"You just pretend that nothing bothers you and then you turn everything into a joke."
"That's a valid observation. Defense mechanisms come in many forms."
"That's ridiculous. l am an easygoing person... who is just trying to be friendly to someone who is obviously terrified of having a friend."
"Fear of intimacy is a common indication of low self-esteem. Perhaps if you stopped to analyze the root cause, you might..."

- Torres, The Doctor, and Paris before Torres shut down The Doctor's voice

"How do you like your first day as chief of security, ensign?"
"It's everything I dreamed of, sir."
"Who says there's no room for advancement on this ship?"

- Chakotay and Lang, when they are among only a handful of the crew still left on Voyager

"You don't think I'm hostile, do you?"
"I, uh... wouldn't describe you that way, no."
"I know that I have a temper, but that doesn't mean that I'm always hostile, does it?"
"No, of course not."
"I am forthright; I speak my mind. That is very different from being hostile."
"Very different"
"And if someone described me that way, they'd be way off the mark, wouldn't they?"
"Way off."
"Then why do you look like you're afraid for your life?"

With this episode, Lisa Klink wanted to devise a story in a style that she was not used to doing for Star Trek: Voyager. "I really wanted to do an ensemble story that was a little more plot-driven," she said, "because a lot of my stuff has been very character-driven." (Cinefantastique, Vol. 29, No. 6/7, p. 113)

The door of Cargo Bay 2 and the section of corridor outside that room were set pieces which were normally used for the holodecks and shuttlebay. (Delta Quadrant, p. 184) In fact, they can be seen outside one of the holodecks at the start of this episode.

The Nyrian corridors were a modified reuse of the Borg interior set from "Unity". (Delta Quadrant, p. 184)

According to the unofficial reference bookDelta Quadrant (pp. 63 & 184), the Nyrian firearms in this episode were stock weapon props; their rifles had apparently been used in TNG: "Unification I", "Unification II", "Starship Mine" and "Gambit, Part I" as well as Voyager's second season premiere, "The 37's", whereas the Nyrian pistols were purportedly previously used as Romulan pistols. The book specifies that the Nyrian rifle props slightly differ, in this case, from how they are shown in their previous appearances as, here, they have an extension added to the barrel.

Allan Kroeker once stipulated that his "only regret" of this entire episode was the Nyrians. He explained, "I thought it would have been nicer if the [Nyrians] were fattening these people up to eat them. [But] all they were doing was taking them from their own environment and putting them in a nice new environment, which was nonetheless a form of imprisonment. I was thinking of the Twilight Zone episode 'To Serve Man.' I thought it would be wonderful if there was just this awful motive that they actually had, and that they were even nastier than they were. I felt that was missing." (The Official Star Trek: Voyager Magazine, issue #15)

This episode achieved a Nielsen rating of 4.7 million homes, and a 7% share. [2]